The invention herein relates to certain teachings disclosed in the applicant's U.S. Pat. application Ser. No. 729,310 filed Oct. 4, 1976, wherein is set forth means for greatly increasing light reflection control sensitivity of a light optic data handling system. These and additional means are incorporated in the present invention so as to increase still further the light reflection control sensitivity within such systems and more particularly in applications thereof requiring a line-at-a-time scanning of viewing surfaces with a beam of radiant energy focused thereon.